1. Field of the Invention
This invention relates to communication connectors constructed to compensate for crosstalk among signal paths. carried through the connectors.
2. Discussion of the Known Art
There is a need for a durable, high-frequency communication connector that compensates for (i.e., cancels or reduces) crosstalk among different signal paths through the connector. As defined herein, crosstalk occurs when signals conducted over a first path, e.g., a pair of terminal contact wires associated with a communication connector, are partly transferred by inductive or capacitive coupling into a second path, e.g., another pair of terminal contact wires in the same connector. The transferred signals produce xe2x80x9ccrosstalkxe2x80x9d in the second path, and such crosstalk degrades existing signals routed over the second path.
For example, a typical industry type RJ-45 communication connector includes four pairs of contact wires defining four different signal paths. In conventional RJ-45 plug and jack connectors, all four pairs of wires extend closely parallel to one another over the length of the connector body. Thus, signal crosstalk may be induced between and among different pairs of connector wires, particularly in a mated plug and jack combination. The amplitude of the crosstalk generally increases as the signal frequencies or data rates increase.
Applicable industry standards for rating the degree to which communication connectors exhibit crosstalk, do so in terms of near-end crosstalk or xe2x80x9cNEXTxe2x80x9d. These ratings are typically specified for mated plug and jack combinations, wherein input terminals on the plug connector are used as a reference plane. Communication links using unshielded twisted pairs (UTP) of copper wire are now expected to support data rates up to not only 100 MHz or industry standard xe2x80x9cCategory 5xe2x80x9d performance, but to meet or exceed xe2x80x9cCategory 6xe2x80x9d performance levels which call for at least 46 dB crosstalk loss at 250 MHz.
U.S. Pat. No. 5,186,647 (Feb. 16, 1993) discloses an electrical connector with crosstalk compensation for conducting high frequency signals. The connector has a pair of metallic lead frames with connector terminals formed at opposite ends of the lead frames. When the lead frames are mounted on a dielectric spring block, three conductors of one lead frame have cross-over sections that align with corresponding cross-over sections of three conductors in the other lead frame. All relevant portions of the ""647 patent are incorporated by reference. U.S. Pat. No. 5,580,270 (Dec. 3, 1996) also discloses an electrical plug connector having crossed pairs of contact strips.
Crosstalk compensation circuitry may also be provided on or within layers of a printed wire board, to which spring terminal contact wires of a communication jack are connected within the jack housing. See U.S. Pat. No. 5,997,358 (Dec. 7, 1999) all relevant portions of which are incorporated by reference. See also U.S. Pat. No. 5,299,956 (Apr. 5, 1994).
U.S. Pat. No. 6,116,964 (Sep. 12, 2000), also incorporated by reference, discloses a communication connector assembly having co-planar terminal contact wires that are spaced a certain distance above a wire board. Base portions of the wires are received in plated openings in the board, and certain pairs of the wires have opposed cross-over sections formed near a line of contact between the wires and a mating connector. A coupling region along the wires beyond the cross-over sections further compensates for crosstalk introduced by the mating connector.
U.S. Pat. No. 6,139,371 issued Oct. 31, 2001, and U.S. Pat. No. 6,165,023 issued Dec. 26, 2000, both of which are assigned to the assignee of the present invention and application, relate to communication connectors in which capacitive crosstalk compensation coupling is provided between leading portions of pairs of terminal contact wires in the connectors. U.S. patent application No. 09/583,503 filed May 31, 2000, and assigned to the assignee of the present invention and application, discloses a communication connector in which parallel plate capacitors are formed at free ends of certain pairs of terminal contact wires for producing crosstalk compensation in the connector.
U.S. Pat. No. 6,176,742 issued Jan. 23, 2001, and assigned to the assignee of the present invention and application, relates to a capacitor compensation assembly for a communication connector wherein terminals of the assembly make electrical contact with certain terminal contact wires of the connector, when the contact wires of the connector are engaged by a mating connector. See also commonly owned U.S. Pat. No. 6,155,881 issued Dec. 5, 2000.
A communication connector which, when connected with a mating connector provides such crosstalk compensation that the connectors meet or exceed Category 6 performance levels, is very desirable in today""s telecommunications environment.
According to the invention, a communication connector assembly includes a wire board having a front edge region, and a number of compensation coupling contacts at the edge region which contacts are coupled to compensation elements selected to produce a desired crosstalk compensation coupling. A number of terminal contact wires extend over the wire board for connection with corresponding terminals of a mating connector along a line of contact. The contact wires have connecting portions for electrically contacting the corresponding terminals of the mating connector wherein the connecting portions have free ends, and base portions arranged to support the contact wires on the board.
The free ends of the terminal contact wires are located ahead of the line of contact, and are formed to deflect toward the wire board and to connect with corresponding ones of the compensation coupling contacts when the mating connector engages the connector assembly. Accordingly, the crosstalk compensation coupling becomes operative at the line of contact between the terminal contact wires and the mating connector, where such coupling can be most effective.
For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawing and the appended claims.